瑞香狼毒（Stellera chamaejasme L.）对高寒草甸系统生长和非生长季节碳氮循环的影响及其花粉化感效应

瑞香狼毒（Stellera chamaejasme L.）是瑞香科（Thymelaeaceae）狼毒属的一种多年生野草，有毒。据调查，从20 世纪60 年代开始至今，狼毒在青藏高原东缘的高寒草甸上不断蔓延、密度不断变大，在一些地段甚至成为优势物种。有关狼毒在高寒草甸蔓延的生态系统效应的研究尚未见报道。本文从系统碳、氮循环的角度，分别研究狼毒在生长和非生长季节对高寒草甸生态系统的影响。同时，从花粉化感的角度，深入研究狼毒对当地同花期物种有性繁殖的影响。系统地研究高寒草甸生态系统物质循环过程，特别是非生长季节微生物和土壤碳氮库的动态变化，有助于揭示狼毒在系统物质循环方面的“物种效应”以及这种效应的季节变化，为丰富有关高海拔生态系统，特别是其非生长季的物质循环的科学理论做出贡献。同时，碳氮循环和花粉化感的研究还有助于深刻地理解狼毒作为一种入侵性很强的杂草的特殊的蔓延机制，从而为狼毒的有效防治、高寒草甸的科学管理提供依据。 针对狼毒在青藏高原高寒草甸上蔓延的生态系统碳氮循环方面的影响，开展以下2 方面的研究：（1）在生长季，研究松潘县尕米寺附近（北纬32°53'，东经103°40'，海拔3190 m）的两种地形（平地和阳坡）条件下狼毒对土壤碳氮循环影响及可能的原因。狼毒和其它几个主要物种（圆穗蓼（Polygonummacrophyllum D. Don var. Macrophyllum），草地早熟禾（Poa pretensis L.），四川嵩草（Kobresia setchwanensis Hand.-Maizz.），鹅绒委陵菜（Potentilla anserina L.var. anserine）和鳞叶龙胆（Gentiana squarrosa Ledeb.）的地上凋落物产量以及地上凋落物和根的化学组成被测量。在有-无狼毒斑块下，各种土壤的库（比如，铵态氮、硝态氮、无机磷和微生物生物量）和周转率（包括净矿化、净硝化、总硝化、反硝化和微生物呼吸速率）被测量和比较。（2）在非生长季节，尤其是春季冻融交替期，选取了两个研究地点——尕米寺和卡卡沟（北纬32°59'，东经103°41'，海拔3400 m），分别测定有狼毒和无狼毒斑块下土壤微生物生物量碳和氮、可溶性有机碳和氮以及铵态氮和硝态氮的动态变化。同时，分别在上述两个地点有-无狼毒的样地上，研究6 个主要物种（狼毒、圆穗蓼、草地早熟禾、四川嵩草、鹅绒委陵菜和鳞叶龙胆）从秋季开始、为期1 年的凋落物分解过程。 针对狼毒花粉化感对同花期其它物种可能的花粉化感作用开展以下工作：在实验室中，用一系列浓度的狼毒花粉水浸提液对与它同花期的其它物种以及自身花粉进行测试，测定花粉萌发率；在野外自然条件下的其它物种的柱头上施用上述浓度的狼毒花粉水浸提液，观测种子结实率，同时，观察狼毒花粉的种间花粉散布数量。 生长季节的研究结果表明，狼毒地上凋落物氮含量比其它几个主要物种更高，而木质素-总氮比更低。狼毒显著地增加其斑块下表层土壤中有机质的含量，而有-无狼毒的亚表层土壤在有机碳和总磷方面没有显著差异。狼毒表土中硝态氮含量在平地和阳坡比无狼毒土壤分别高113%和90%。狼毒表土中微生物生物量碳和氮量显著高于无狼毒表土。无论是平地还是阳坡，狼毒土壤的总硝化和微生物呼吸速率显著高于无狼毒土壤；而它们的反硝化速率只在平地有显著的差异。狼毒与其它物种间地上凋落物的产量和质量的差异可能是导致有-无狼毒土壤碳氮循环差异的原因。我们假设，狼毒可能通过增加贫氮生态系统土壤中的有效氮含量提高其入侵能力。 非生长季的研究结果表明，在青藏高原东缘的高寒草甸上，土壤微生物生3物量在11 月的秋-冬过渡期达到第一个峰值；在春季的冻融交替期，微生物生物量达到第二个峰值后又迅速降低。无机氮以及可溶性有机碳氮与微生物生物量有相似的变化过程。微生物碳氮比呈现显著的季节性变化。隆冬季节的微生物生物量碳氮比显著高于生长旺季的微生物碳氮比。这种变化可能暗示冬、夏季微生物的群落组成和对资源的利用有所不同。有-无狼毒斑块下土壤微生物和土壤碳、氮库一般只在秋-冬过渡期有显著差异，有狼毒土壤微生物生物量和土壤碳、氮库显著高于无狼毒土壤；而在之后的冬季和春季没有显著差异。所有6 个物种凋落物在非生长季分解率为24%-50%，均高于生长季的10%到30%。其中在秋-冬过渡期，凋落物开始埋藏的两周时间内，分解最快，达10%-20%。不同物种凋落物全年的分解率和分解过程有显著差异。圆穗蓼在全年的分解都较缓慢（非生长季26%，生长季15%），草地早熟禾和四川嵩草等全年的分解速率比较均匀（非生长季和生长季均为30%，非生长季略高），而狼毒在非生长季分解较快（约50%），而在接下来的生长季分解变得缓慢（约12%）。所有物种的凋落物氮含量在非生长季下降，而在随后的生长季上升。 实验室的花粉萌发试验证明，狼毒花粉对自身花粉萌发没有自毒作用，而其它受试的所有物种（圆穗蓼，秦艽（Gentiana macrophylla Pall. var. fetissowii），湿生扁蕾（Gentianopsis paludosa (Hook. f.) Ma var. paludosa），鳞叶龙胆，椭圆叶花锚（Halenia elliptica D. Don var. elliptica），蓝钟花（Cyananthus hookeri C. B.Cl. var. grandiflorus Marq.），小米草（Euphrasia pectinata Ten.），川西翠雀花（Delphinium tongolense Franch.），高原毛茛（Ranunculus tanguticus (Maxim.)Ovcz. var. tanguticus）和鹅绒委陵菜）的花粉萌发率随着狼毒花粉浸提液浓度的增加呈显著的非线性降低。大约3 个狼毒花粉的浸提液就可以抑制受试的多数物种的50%的花粉萌发。在鳞叶龙胆和小米草柱头上狼毒花粉的数量分别为5.76 个和3.35 个。狼毒花粉散布数量的差异最可能的原因在于是否有共同的传粉昆虫。花的形状（辐射对称VS 左右对称）、植株或花的密度以及花期重叠性可以部分解释这种差异。在野外试验中，我们发现6 个物种（秦艽、湿生扁蕾、鳞叶龙胆、椭圆叶花锚、蓝钟花和小米草）的种子结实率随狼毒花粉浸提液浓度的增加呈显著的非线性降低。鳞叶龙胆和小米草柱头上狼毒花粉的数量（分别是5.76 个和3.35 个）分别达到了抑制它们63%和55%种子结实率的水平。因此，狼毒对鳞叶龙胆和小米草可能存在明显的花粉化感抑制作用。狼毒周围的物种可能通过花期在季节或昼夜上的分异避免受到狼毒花粉化感的影响或者通过无性繁殖来维持种群繁衍，因此狼毒通过花粉化感作用对其周围物种繁殖的影响程度还需要进一步地研究。如果狼毒的花粉化感抑制作用确实存在，那么它可能成为一种自然选择压力，进而影响物种的进化。 Stellera chamaejasme L., a perennial toxic weed, has emerged and quicklydominated and spread in the high-frigid meadow on the eastern Tibetan Plateau ofChina since the 1960s. In the present study, effects of S. chamaejasme on carbon andnitrogen cycles on the high-frigid meadow on the eastern Qinghai-Tibetan Plateau ingrowing and non-growing season, and its pollen allelopathic effects on the sympatricspecies were determined. The present study that focused on carbon and nitrogencycles, especially on microbial biomass and pools of carbon and nitrogen innon-growing season, could profoundly illuminate plant-species effects on carbon andnutrient cycles and its seasonal pattern and help to understand spread mechanism ofS. chamaejasme as an aggressive weed. The present study also contributed to furtherunderstand carbon and nutrient cycles on alpine regions in non-growing season andprovide a basis on weed control of S. chamaejasme and scientific management in thehigh-frigid ecosystem. Effects of S. chamaejasme on carbon and nitrogen cycles on the high-frigidmeadow on the eastern Qinghai-Tibetan Plateau were determined. The study couldbe divided into two parts. (1) In the growing season, we quantified the effects of S.chamaejasme on carbon and nitrogen cycles in two types of topographic habitats, theflat valley and the south-facing slope, where S. chamaejasme was favored to spreadlitter and root were measured to explain the likely effects of S. chamaejasme on soilcarbon and nutrient cycles. The sizes of various soil pools, e.g. nitrite, ammonium,inorganic phosphorus and microbial biomass, and turnover rates including netmineralization, gross nitrification, denitrification and microbial respiration weredetermined. (2) In the non-growing season study, microbial biomass carbon andnitrogen, soluble organic carbon and nitrogen, ammonium and nitrate weredetermined through the non-growing season, especially in the processes offreeze-thaw of spring in two high-frigid sites, i.e. Kaka valley and Gami temple, onthe eastern Qinghai-Tibetan Plateau. Meanwhile, litter decomposition of six commonspecies, including Stellera chamaejasme L., Polygonum macrophyllum D. Don var.Macrophyllum, Poa pretensis L., Kobresia setchwanensis L., Potentilla anserina L.var. anserine and Gentiana squarrosa Ledeb., were also examined under theabove-mentioned experimental design through one whole-year, which began in theautumn in 2006. In the study of pollen allelopathy, several work, including in vitro study oneffects of extract of pollen from S. chamaejasme on sympatric species and pollenfrom itself, field experiments on effects of pollen extract with the same regime ofconcentrations on seed set and field observation on heterospecific pollen transfer ofS. chamaejasme to six of those sympatric species has been done. The results in the growing season showed that aboveground litter of S.chamaejasme had higher tissue nitrogen and lower lignin: nitrogen ratio than thoseco-occurring species. S. chamaejasme significantly increased topsoil organic matter,whereas no significant differences were found for organic C and total P in subsoilbetween under-Stellera and away-Stellera locations. The nitrate in Stellera topsoilwas 113% and 90% higher on the flat valley and on the south-facing slope,respectively. Both microbial biomass C and N were significantly higher in Stelleratopsoil. Gross nitrification and microbial respiration were significantly higher inStellera topsoil both on the flat valley and on the south-facing slope, whereassignificant differences of denitrification were found only on the flat valley. Thedifferences in the quantity and quality of aboveground litter are a likely mechanismresponsible for the changes of soil variables. We assumed that S. chamaejasme couldenhance their spread by increasing nutrient availability in N-deficient ecosystems. The results in the non-growing season showed that microbial biomass achievedthe first summit in late autumn and early winter on the eastern Qinghai-TibetanPlateau. In the stages of freeze-thaw of spring, microbial biomass firstly achieved thesecond summit and subsequently sharply decreased. Inorganic nitrogen, solubleorganic carbon and nitrogen had a similar dynamics with that of microbial biomass.Ratio of microbial biomass carbon and nitrogen had an obviously seasonal pattern.The highest microbial C: N were in the non-growing season, which weresignificantly higher than those in the growing season. The seasonal pattern inmicrobial biomass C: N suggested that large changes in composition of microbialpopulation and in resources those used by microbes between summer and winter.Generally, microbial biomass and pools size of carbon and nitrogen in Stellera soilwere significantly higher than those under adjacent locations in late autumn andearly winter, but there were not significant differences in winter and in spring. Litterof all the focal species (Stellera chamaejasme L., Polygonum macrophyllum D. Donvar. Macrophyllum, Poa pretensis L., Kobresia setchwanensis Hand.-Maizz.,Potentilla anserina L. var. anserine and G. squarrosa Ledeb.) decomposed about24%-50% in the non-growing season, which were higher than those in the growingseason (ranged from 10% to 30%). Litter decomposed 10%-20% within the first twoweeks in late autumn and early winter. Significant differences in the whole-yeardecomposition rate and in the processes of decomposition were found among species.Polygonum macrophyllum decomposed slowly through the whole year (26% and15% in the non-growing season and in the growing season, respectively). Certainspecies, such as P. pretensis L. and K. setchwanensis, decomposed at a similar rate(30% both in the non-growing and in the growing season, slightly higher in the8growing season than those in the growing season), whereas S. chamaejasmedecomposed more rapidly (about 50%) in the non-growing season and subsequentlydecomposition became slow (about 12%) in the growing season. Litter nitrogencontents of all the focal species firstly decreased in the non-growing season and thenincreased in the growing season. In vitro experiments of pollen allelopathy, the results showed that pollen from S.chamaejasme was not autotoxic, whereas pollen germination in all the sympatricspecies (Polygonum macrophyllum D. Don var. Macrophyllum, Gentianamacrophylla Pall. var. fetissowii, Gentianopsis paludosa (Hook. f.) Ma var. paludosa,Gentiana squarrosa Ledeb., Halenia elliptica D. Don var. elliptica, Cyananthushookeri C. B. Cl. var. grandiflorus Marq., Euphrasia pectinata Ten., Delphiniumtongolense Franch., Ranunculus tanguticus (Maxim.) Ovcz. var. tanguticus andPotentilla anserina L. var. anserina) decreased nonlinearly as the increasingconcentrations of extract of pollen from S. chamaejasme. Pollen Extract of threepollens from S. chamaejasme generally inhibited 50% pollen germination of most ofthe focal species. 5.76 and 3.35 pollens from S. chamaejasme were observed in fieldon stigmas of G. squarrosa and E. pectinata, respectively. Differences inheterospecific pollen transfer of S. chamaejasme could be attributed to the primaryreason whether they shared common pollinators. Flower morphology (e.g.zygomorphic or actinomorphic), plant or floral density and concurrence in floweringphonologies could explain, in part, the differences in heterospecific pollen transfer.In field experiments, the results showed that seed set in six sympatric species(Gentiana macrophylla Pall. var. fetissowii, Gentianopsis paludosa (Hook. f.) Mavar. paludosa, Gentiana squarrosa Ledeb., Halenia elliptica D. Don var. elliptica,Cyananthus hookeri C. B. Cl. var. grandiflorus Marq. and Euphrasia pectinata Ten.)decreased nonlinearly as the increasing concentrations of extract of pollen from S.chamaejasme. According to the nonlinear curves, the amounts of pollens from S.chamaejasme on stigmas of G. squarrosa and of E. pectinata (i.e. 5.76 grains and3.35 grains, respectively) could reduce 63% and 55% seed set of G. squarrosa and ofE. pectinata, respectively. Thus, allelopathic effects of S. chamaejasme on G.squarrosa and E. pectinata could be realistic. The sympatric species of S.chamaejasme could avoid pollen allelopathy of S. chamaejasme to sustainthemselves. This highlights the need to study how much pollen allelopathy in S.chamaejasme influences the sympatric species through divergence in seasonal ordiurnal flowering phonologies or through asexual reproduction. If pollen allelopathyin S. chamaejasme was confirmed, it could be as a pressure of natural selection andthus play an important role in species evolution.

遮荫与外源脱落酸喷施对青杨(Populus cathayana Rehd.)不同种群抗旱性的影响

杨树具有分布广、适应性强的特征，在生态环境治理和解决木材短缺方面均占有重要位置。青杨(Populus cathayana Rehd.)是青杨派树种的重要成员之一，也是生长较迅速、易繁殖的重要杨树资源。本研究选取了来自不同气候地区的青杨两种群为材料，采用植物生态学、生理学和生物化学的研究方法，系统地研究了青杨对干旱与遮荫、干旱与外源脱落酸(ABA)喷施的生长、形态、生理和生化响应及种群间差异，研究成果可为我国干旱半干旱地区的造林以及生态恢复提供理论依据和科学指导。主要研究结论如下：1.青杨在干旱胁迫下的适应机制为：生长性状及生物量的分配变化：干旱胁迫下虽然植株生长受抑，株高、基茎及各部分生物量都显著减小，但有相对较多的生物量向根部分配，根/冠比以及细/粗根比增加。青杨对干旱胁迫的光合作用表现为：干旱胁迫降低了青杨的净光合速率、蒸腾速率、气孔导度以及光合氮利用效率，提高了瞬时用水效率。干旱还引起了活性氧的产生，使得膜脂过氧化产物丙二醛(MDA)增加，同时也增强了植物抗氧化酶系统(如超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性的增加)及非酶系统的能力(如抗坏血酸(AsA)含量的增加)。干旱降低了植物叶片的相对含水量，而促进了渗透调节物质(游离脯氨酸及可溶性糖)的积累，增加了植物的渗调能力。干旱下青杨两种群的内源ABA含量显著增加，碳同位素组分(δ13C)也显著提高。这些结果证明植物遭受干旱胁迫后发生一系列的形态、生理和生化响应，这些变化能提高植物在干旱下的存活和生长能力。2.青杨两种群对干旱胁迫反应的种群差异：与来自湿润地区的汉源种群相比，来自干旱地区的乐都种群在干旱条件下生物量向根系分配的可塑性更强，同时具有更强的抗氧化系统能力，所受到活性氧的伤害也更少，并且累积更多的脯胺酸和ABA，具有更高的δ13C。这些都说明了乐都种群对干旱的适应性比汉源种群更强。两种群对干旱的响应差异应归于它们的用水策略的不同：汉源种群来自湿润地区，采用了耗水型的用水策略，抗旱能力较弱；而乐都种群，来自干旱地区，通常采用节水型的用水策略，有更强的抗旱能力。3.遮荫对青杨两种群抗旱性的影响：遮荫对青杨抗旱性的影响决定于遮荫程度的不同，我们的结果表明中度的遮荫可以有效的提高干旱下植物的生长，对干旱胁迫有明显的缓解作用，具体体现在中度遮荫下受旱植物的叶片相对含水量得到提高，使得植物体内水分状况得到了改善；光合速率并未降低，植物光合氮利用效率增加，说明中度的遮荫并未明显限制植物的碳获得；抗氧化酶活性与膜脂过氧化产物MDA含量的同时降低，说明中度遮荫下所受到的活性氧伤害减少；中度遮荫下的ABA及δ13C的变化也不如在全光下变化明显，这也说明中度遮荫缓解了干旱胁迫。但是重度的遮荫却对干旱胁迫有明显的加剧作用，主要表现在重度遮荫降低了植物的光合速率，严重抑制了植物的生长；同时重度遮荫下脯胺酸含量和抗氧化酶活性的急剧下降，导致了植物渗调能力的下降及膜脂过氧化产物MDA的显著升高；重度遮荫还显著降低了内源ABA的累积和δ13C，降低了植物的抗旱能力。此外，青杨两种群在对干旱和遮荫的响应中，也表现出种群差异。汉源种群，来自湿润且年日照辐射较少的地区，表现出相对更强的耐荫性和需水性。而乐都种群，来自干旱且年日照辐射丰富的地区，表现出相对更强的耐旱性和需光性。这说明了植物对环境胁迫的耐受性是其长期适应原生境的结果，并且来自不同气候地区的两种群在面临环境胁迫时会采取不同的生存策略。4. 外源ABA喷施对青杨两种群抗旱性的影响：外源ABA的喷施可以提高两种群的抗旱性，具体表现为外源ABA喷施促进了青杨根系的生长，显著提高了干旱下植物的根/冠比和细/粗根比，减少了比叶面积；在生理生化方面，外源ABA降低了干旱下植物叶片的气孔导度，降低了蒸腾速率和净光合速率，但提高了瞬时用水效率，提高了叶片的相对含水量，增加了干旱下植物的保水能力。外源ABA进一步增加了干旱下植物内源ABA的积累，促进了植物渗调物质如脯胺酸和可溶性糖的积累，增加了抗氧化酶系统(如SOD、APX、CAT)的活性和非酶系统AsA的含量，降低了活性氧(如超氧阴离子(O2和过氧化氢(H2O2))对植株的伤害。此外，外源ABA还进一步提高了干旱下植物的δ13C，提高了植物的长期用水效率，由此提高了植物的抗旱能力。另一方面，两种群对外源ABA和干旱的响应也有所差别。来自湿润地区的汉源种群，对干旱较为敏感，所受干旱的影响也较大，而外源ABA的喷施对汉源种群抗旱性的提高作用也更为突出。乐都种群，由于其长期适应干旱地区的生长，本身已具有较强的抗旱能力，因此外源ABA喷施对其抗旱性的提高不如对汉源种群的效果明显。由此我们可以得出对于一些抗性弱或干旱敏感的物种或者种群，可以采用外施ABA的方法来提高其抗性。Poplars play an important role in lumber supply, and are important component ofecosystems due to their wide distribution and well adaptation. Populus cathayana Rehd.,which belongs to Populus Sect. Tacamahaca Spach, is one of the most important resources ofpoplars for its fast growth and reproductive. In this study, different populations of P.cathayana were used as experiment material to investigate the adaptability to drought stressand population differences in adaptability, and the effects of shade and exogenous abscisicacid (ABA) application on the drought tolerance. Our results could provide a strongtheoretical evidence and scientific direction for the afforestation, and rehabilitation ofecosystem in the arid and semi-arid area, and provide a strong evidence for adaptivedifferentiation of different populations, and so may be used as criteria for species selectionand tree improvement. The results are as follows:1. A large set of parallel response to drought stress: Drought stress caused pronouncedinhibition of the growth and increased relatively dry matter allocation into the root. For thetwo populations, the shoot height, basal diameter and total biomass were decreased but theroot/shoot ratio and fine root/coarse root ratio were increased under drought conditions；Drought stress caused pronounced inhibition of photosynthesis, decreased the stomatalconductance, transpiration rate, and photosynthetic nitrogen-use efficiency (PNUE) butincreased the instantaneous water use efficiency. Drought significantly improved the levels ofreactive oxygen species and malondialdehyde (MDA) and to induce the entire set ofantioxidative systems including the increase of activities of superoxide dismutase (SOD),ascorbate peroxidase (APX), catalase (CAT) and ascorbate (AsA) content. Drought decreased the leaf relative water content (RWC) but improved the capability of osmotic adjustmentindicated by the higher proline accumulation. Drought also increased the ABA content andcarbon isotope composition (δ13C), which indicating the long period water use efficiency wasimproved under drought. These results demonstrate that there are a large set of parallelchanges in the morphological, physiological and biochemical responses when plants areexposed to drought stress; these changes may enhance the capability of plants to survive andgrow during drought periods.2. Difference in adaptation to drought stress between contrasting populations of P.cathayana: Compared with the Hanyuan population (wet climate), the Ledu population (dryclimate) showed higher root/shoot ratio and water use efficiency, exhibited higherantioxidative systems capability thus resulting in less oxidative damage, accumulated moreABA and free proline content under drought conditions. The results suggested that there weredifferent water-use strategies between the two populations. The Ledu population, whichcomes from dry climate region, with higher drought tolerance, may employ a conservativewater-use strategy, whereas the Hanyuan population, which comes from wet climate, withlower drought tolerance, may employ a prodigal water-use strategy. These variations indrought responses may be used as criteria for species selection and tree improvement.3. The effects of shade on the drought tolerance: The reduction in the availability of lightand water affected the morphological and physiological responses of the two P. cathayanapopulations. In addition, the light environment modified the growth responses of P.cathayana seedlings to varying water environments in different ways depending upon theintensity of the light levels considered. There is an apparent alleviation to drought effects bymoderate shade in P. cathayana seedlings, as indicated by the higher leaf RWC, and unchanged net photosynthesis and PNUE, as well as by the lower antioxditative enzymeactivity, MDA, ABA and δ13C levels, which implied moderate shade did not significantlylimited the carbon acquisition or inhibited the plant growth, but ameliorated the detrimentaleffects of drought. On the other hand, an apparent aggravation to drought effects by severeshade was also observed, as indicated by the pronounced decrease of plant growth and net photosynthesis, the lower total biomass, ABA level, δ13C, free proline content andantioxditative enzyme activity and higher MDA accumulation. By contrast, the twopopulations showed different responses to shade and drought. The Hanyuan population,which comes from a riparian basin having a relatively wet climate and less annual solarradiation, is more sensitive to drought but more tolerant to shade. The Ledu population, whichcomes from a mountainous plateau with less rainfall and with more annual solar radiation, ismore tolerant to drought but more sensitive to shade. The results demonstrated that theendurance of plants to stress is a result of long-term evolution and adaptation to theenvironment, as suggested by the different strategies employed by the P. cathayanapopulations originating from contrasting habitats when they were exposed to drought andshade.4. The effects of exogenous ABA application on the drought tolerance: For bothpopulations under drought conditions tested, exogenous ABA application significantlyimproved the root/shoot ratio, fine root/coarse root ratio, and decreased the specifical leaf area.On the physiological and biochemical traits, exogenous ABA application significantlydecreased stomatal conductance, transpiration rate and net photosythesis but increased theinstance water use efficiency and leaf RWC. On the other hand, exogenous ABA applicationsignificantly increased endogenous ABA, proline, solube sugar and AsA content, as well asSOD, APX and CAT activities, thus reduced the damage of reactive oxygen species. Moreover,the long period water use efficiency as indicated by δ13C was also improved by exogenousABA application. In additionally, there was different responsive between the two populationsto drought and exogenous ABA application. The Hanyuan population, which comes from wetclimate region, is more sensitive to drought, and the effect of exogenous ABA is moreobviously than that in the Ledu population, which comes from dry climate region and is moredrought-responsive. Therefore, we can use exogenous ABA application to improve theresistance of plants, especially for the drought- sensitive species or populations.

克隆植物东方草莓对异质生境的适应对策

克隆植物被认为比非克隆植物更宜于利用异质性环境。在复杂的空间异质环境中，克隆植物可能形成了各种有效利用环境异质性的适应对策。对于克隆植物适应机制的研究，前人已做了大量的工作，特别是从形态和生物量分配等方面对简单异质生境下克隆植物的克隆整合和克隆分工进行了详细的研究。本研究以分布广泛的克隆植物东方草莓（Fragaria orientalis）作为研究对象，应用野外调查和实验生态学方法，采用多对比度单资源模型和不同向双资源模型，从形态和生理生态的角度，研究复杂异质生境下克隆植物的整合和分工及其耗益问题，分析不同类型的生境对克隆植物整合和分工的修饰作用，进而探讨克隆植物对异质生境的适应策略。克隆构型和分株种群特征是植物克隆生长及其生态适应对策研究的基本内容。本文通过野外调查，研究在不同光照条件下东方草莓克隆构型、分株种群特征以及点分布格局。结果表明：东方草莓的克隆构型随光照发生相应的变化，低光照下其匍匐茎节间长和分枝角度均增大而分枝强度减小；随光照减弱，东方草莓分株种群的生物量、根冠比和分株种群密度显著降低；不同光照下东方草莓分株均以随机分布为主但不同尺度下有所差异，其分布格局强度依次为旷地<林缘<林下。结合克隆植物对资源的利用对策，探讨了克隆构型和分株种群特征以及分布格局随环境条件变化的生态适应意义。不同生境斑块条件下克隆植物可能采取不同的适应对策。采用盆栽实验，研究不同水分对比度下克隆整合及其生理生态特征，并对单向和交互资源中东方草莓的克隆整合做了对比研究。结果显示：高的水分对比度能够促进东方草莓的克隆整合，并能刺激相连分株增加光合作用，东方草莓体内的氧化—抗氧化系统也II随对比度做出相应的反应。耗-益分析表明胁迫分株的受益是以供给分株的损耗为代价的，但从克隆片段总体来说是受益的。单向资源中东方草莓生长的绝对值高于交互资源，但耗-益分析表明生长于交互资源下东方草莓的克隆整合获益大于生长于单向资源下东方草莓的克隆整合获益。长期生长于特定生境的克隆植物，在进化过程中其克隆整合和克隆分工在对资源异质性的适应策略方面可能有所侧重。采用盆栽实验对来自不同海拔梯度的东方草莓的克隆整合和克隆分工对异质资源的适应对策进行了研究。实验结果表明，来自高海拔的东方草莓可塑性较差。来自两个海拔的东方草莓对切断匍匐茎的表现有所差异，总体上切断匍匐茎对来自高海拔的东方草莓影响更大些。另外，来自高海拔的东方草莓表现出更高的克隆分工。IIIClonal plants are known to be more suitable for the habitats of heterogeneousresources than nonclonal plants, perhaps due to their well developed adaptivestrategies to environmental heterogeneity. Many studies have been done on theadaptive mechanisms of clonal plants, especially on the clonal integration anddivision of labor with morphology and biomass allocation under simpleheterogeneous habitats. Based on field surveys, laboratory experiments, multi-contrastunidirectional resource model and reciprocal resource model, Fragaria orientalis, aRosaceae stoloniferous herb that widely distributes in China, was used to study thisplant’s morphological and physiological responses to complicated heterogeneoushabitats in terms of its clonal integration, division of labor and cost-benefit, as well astheir modifications by different habitats, so as to better understand the adaptivestrategies of clonal plants under heterogeneous environments.Clonal architecture and ramet population characteristics are of the major concernin the studies on growth and adaptive strategies of clonal plants. Clonal architecture,ramet population characteristics and spatial point pattern of F. orientalis underdifferent light intensity were studied with field observations. The results showed that,clonal architecture changed with light availability: Internode-lengths and branchangels of stolons were larger while branch intensities were smaller under lower lightintensity than those under higher light intensity; Biomass of ramet population,root-shoot ratio and density of ramet population decreased significantly with reduce oflight intensity; Under all light intensities, spatial pattern of ramets was mainlyrandomly distributed but it changed with different scales, with pattern intensity as:open space < forest edge < understory. Adaptation significance of the clonal architecture, the ramet population characteristics and the spatial pattern changing withdifferent environments was discussed according to these results.Clonal plants may take different adaptive strategies under different patches. Withpot culture, clonal integration and physiological parameters of F. orientalis underdifferent water contrasts were studied, and clonal integration under unilateralresources and reciprocal resources were also compared. The results suggested that,high water contrast improve the clonal integration of F. orientalis and increase thephotosynthesis of connected ramets. Oxidative and antioxidative system of F.orientalis also responded with changing water contrasts. According to cost-benefitanalysis, the drought-stressed ramets obtained benefits from the connectedwell-watered ramets, and as a whole, the clonal fragment could also get benefits.Growth of F. orientalis in homogeneous resources was better than that inheterogeneous resources, but the whole plant got more benefit through clonalintegration in heterogeneous resources than in homogeneous resources.Pot culture experiments were also used to study the adaptive strategies inutilizing heterogeneous resources by the plant populations from different altitudes.The results showed that, F. orientalis from alpine zones were shorter and lessexpanded with poorer clonal plasticity than those from middle mountains. F.orientalis from two different altitudes showed different responses to stolon severing,and as a whole, stolon severing had more influence on F. orientalis from alpine zones.In addition, F. orientalis from alpine zones exhibited higher division of labor, whichsuggested that clonal plants from different habitats develop their own adaptivemechanisms in their clonal integration and division of labor in response toenvironmental heterogeneity.

干旱胁迫与施N条件下白刺花（Sophora davidii）幼苗生长及其适应机制

干旱环境常常由于多变的降水事件和贫瘠土壤的综合作用，表现出较低的生产力和较低的植被覆盖度。全球性的气候变暖和人类干扰必将使得干旱地区缺水现状越来越严竣。贫瘠土壤环境中已经很低的有效养分含量也将会随着干旱的扩大而越来越低。干旱与半干旱系统中不断加剧的水分与养分的缺失将严重限制植物的生长和植被的更新，必然会使得已经恶化的环境恶化速率的加快、恶化范围的加大。如何抑制这种趋势，逐步改善已经恶化的环境是现在和将来干旱系统管理者面临的主要关键问题。了解干旱系统本土植物对未来气候变化的适应机制，不仅是植物生态学研究的重要内容，也对人为调节干旱环境，改善干旱系统植被条件，提高植被覆盖度具有重要的实践意义。 本研究以干旱河谷优势灌木白刺花（Sophora davidii）为研究对象，通过两年大棚水分和施N控制实验和一个生长季野外施N半控制实验，从植物生长－生理－资源利用以及植物生长土壤环境特征入手，系统的研究了白刺花幼苗生长特性对干旱胁迫和施N的响应与适应机制，并试图探讨施N是否可调节干旱系统土壤环境，人工促进干旱条件下幼苗定居，最终贡献于促进植被更新实践。初步研究结论如下： 1）白刺花幼苗生长、生物量积累与分配以及水分利用效率对干旱胁迫和施N处理的适应白刺花幼苗株高、基径、叶片数目、叶面积、根长、生物量生产、相对含水量和水分利用效率随着干旱胁迫程度的增加而明显降低，但地下部分生物量比例和R/S随着干旱胁迫程度的增加而增加。轻度施N处理下幼苗株高、基径、叶片数目、叶片面积和生物量生产有所增加。但重度施N处理下这些生长指标表现出微弱甚至降低的趋势。严重干旱胁迫条件下，幼苗叶面积率、R/S、相对含水量和水分利用效率也以轻度施N处理为最高。 2）白刺花幼苗叶片光合生理特征对干旱胁迫和施N处理的适应叶片光合色素含量和叶片光合效率随着干旱胁迫程度的增加而显著降低，并且PS2系统在干旱胁迫条件下表现出一定程度的光损害。但是比叶面积随着干旱胁迫程度的增加而增加。在相对较好水分条件下幼苗净光合速率的降低可能是因为气孔限制作用，而严重干旱胁迫条件下非气孔限制可能是导致幼苗叶片光合速率下降的主要原因。叶片叶绿素含量、潜在光合能力、羧化效率、光合效率以及RUBP再生能力等在施N处理下得到提高，并因而改善干旱胁迫条件下光合能力和效率。虽然各荧光参数对施N处理并无显著的反应，但是干旱胁迫条件下qN和Fv/Fm在轻度施N处理下维持相对较高的水平，而两年连续处理后在严重干旱胁迫条件下幼苗叶片光合效率受到重度施N处理的抑制，并且Fv/Fm和qN也在重度施N处理下降低。 3）白刺花幼苗C、N和P积累以及N、P利用效率对干旱胁迫和施N处理的适应白刺花幼苗C、N和P的积累，P利用效率以及N和P吸收效率随干旱胁迫程度的增加而显著降低，C、N和P的分配格局也随之改变。在相同水分处理下，C、N和P的积累量、P利用效率以及N和P吸收效率在轻度施N处理下表现为较高的水平。然而，C、N和P的积累量和P利用效率在重度施N处理下不仅没有表现出显著的正效应，而且有降低的趋势。另外，在相同水分条件下白刺花幼苗N利用效率随着施N强度的增加而降低。 4）白刺花幼苗生长土壤化学与微生物特性对干旱胁迫和施N的适应白刺花幼苗生长土壤有机C、有效N和P含量也随干旱胁迫程度的增加而明显降低。干旱胁迫条件下土壤C/N、C/P、转化酶、脲酶和碱性磷酸酶活性的降低可能表明较低的N和P矿化速率。尽管微生物生物量C、N和P对一个生长季干旱胁迫处理无显著反应，但微生物生物量C和N在两年连续干旱胁迫后显著降低。土壤有机C和有效P含量在轻度施N处理下大于重度施N处理，但是有效N含量随着施N强度的增加而增加。微生物生物量C和N、碱性磷酸酶和转化酶活性也在轻度施N处理下有所增加。但是碱性磷酸酶活性在重度施N处理下降低。 5）野外条件下白刺花幼苗生长特征及生长土壤生化特性对施N的适应植物生长、生物生产量、C的固定、N、P等资源的吸收和积累、其它受限资源的利用效率（如P）在轻度施N处理下均有所增加，但N利用效率有所降低。幼苗生物生产量及C、N和P等资源的分配格局在轻度施N处理下也没有明显的改变。白刺花幼苗叶片数目、生物生产量和C、N、P的积累量在重度施N处理下虽然也相对于对照有所增加，但幼苗根系长度显著降低。生物量及资源（生物量、C、N、P）在重度施N处理下较多地分配给地上部分（主要是叶片）。另外，土壤有机C、全N和有效N含量随外源施N的增加而显著增加，土壤pH随之降低，但土壤全P含量并无显著反应。其中有机C含量和有效P含量以轻度施N处理最高。微生物生物量C、N和P在轻度施N处理下也显著增加，而微生物生物量C在重度施N处理下显著降低。同时，转化酶、脲酶、碱性磷酸酶和中性磷酸酶活性在施N处理下也明显的提高，但酸性磷酸酶和过氧化氢酶活性显著降低，其中碱性磷酸酶和中性磷酸酶活性以轻度施N处理最高。 综合分析表明，干旱河谷水分和N严重限制了白刺花幼苗的生长。施N不能完全改变干旱胁迫对白刺花幼苗的抑制的作用，但是由于施N增加土壤N有效性，改善土壤一系列生物与化学过程，幼苗的生长特性也对施N表现出强烈的反应，表现为植物结构与资源分配格局的改善，植物叶片光合能力与效率的提高，植物生长以及利用其他受限资源（如水分和P）的效率的增加，致使植物自身生长及其生长环境在干旱环境下得到改善。但是过度施N不仅不能起到改善干旱胁迫下植物生长环境、促进植物生长的作用，反而在土壤过程以及植物生长过程中加重干旱胁迫对植物的伤害。因此，建议在采用白刺花作为先锋种改善干旱河谷系统环境的实践中，可适当施加N以改善土壤环境，调节植物利用与分配资源的效率，促进植物定居，得到人工促进种群更新的目的。但在实践过程中也要避免过度施N。 Arid regions of the world are generally noted for their low primary productivity which is due to a combination of low, unpredictable water supply and low soil nutrient concentrations. The most serious effects of global climate change and human disturbances may well be those which related to increasing drought since drought stress has already been the principal constraint in plant growth. The decline in total rainfall and/or soil water availability expected for the next decades may turn out to be even more drastic under future warmer conditions. Nevertheless, water deficit is not the only limiting factor in arid and semiarid environments. Soils often suffer from nutrient (especially N and P) deficiencies in these ecosystems, which can also be worsened by climate change. How to improve the poor soil quality and enhance the vegetation coverage is always the problem facing ecosystem managers. The adaptive mechanisms of native plant to future climate change is always the focus in plant ecology, it also plays important roles in improving vegetation coverage by manual controlled programmes. Sophora davidii is a native perennial shrub of arid valleys, which is often predominant on eroded slopes and plays a vital role in retaining ecological stability in this region. It has been found that S. davidii was better adapted to dry environment than other shrubs, prompting its use for re-vegetation of arid lands. A two-years greenhouse experiment and a field experiment were conducted in order to understand the adaptation responses of Sophora davidii seedlings to different water and N conditions, and further explore if additional N supply as a modified role could enhance the adaptation ability of S. davidii seedlings to dry and infertile environment. Two-month old seedlings were subjected to a completely randome design with three water (80%, 40% and 20% water field capacity (FC)) and three N supply (N0: 0, Nl: 92 and Nh: 184 mg N kg-1 soil) regimes. Field experiment was arranged only by three N supplies in the dry valley. 1) The growth, biomass partitioning and water-use efficiency of Sophora davidii seedlings in respond to drought stress and N supply Seedlings height, basal diameter, leaf number, leaf area, root length, biomass production, relative water content (RWC) and WUE were decreased with increase of drought stress. An increase in below-ground biomass was observed indicating a higher root/shoot ratio (R/S) under drought stress conditions. Low N supply increased seedlings height, basal diameter, leaf number, leaf area, and biomass production, but decreased root length. In contrast, these growth characteristics showed little or negative effect to high N supply treatment. Leaf percentages increased with increase of N supply, but fine root percentages decreased. In addition, Low N supply rather than the other two N treatments increased leaf area ratio (LAR), leaf/fine root mass ratio (L/FR), R/S and RWC under severe drought stress (20%FC), even though these parameters could increase with the high N supply treatment under well-watered condition (80%FC). Moreover, Low N supply also increased WUE under three water conditions, but high N supply had little effect on WUE under drought stress conditions (40%FC and 20%FC). 2) Leaf gas exchange and fluorescence parameters of Sophora davidii seedlings in respond to drought stress and N supply Leaf area (LA), photosynthetic pigment contents, and photosynthetic efficiency were decreased with increase of drought stress, but specific leaf area (SLA) increased. Photodamage in photosystem 2 (PS2) was also observed under drought stress condition. The decreased net photosynthetic rate (PN) under relative well-watered water conditions might result from stomatal limitations, but the decreased PN under other hand, photosynthetic capacity by increasing LA, photosynthetic chlorophyll contents, Pnmax, CE, Jmax were increased with increase N supply, and photosynthetic efficiency was improved with N supply treatment under water deficit. Although N supply did a little in alleviating photodamages to PS2 caused by drought stress, low N supply enhanced qN and kept relative high Fv/Fm under drought stress condition. However, high N supply inhibited leaf photosynthetic efficiency, and declined Fv/Fm and qN under severe drought stress condition after two year continues drought stress and N supply. 3) Carbon accumulation, nitrogen and phosphorus use efficiency of Sophora davidii seedlings in respond to drought stress and N supply C, N and P accumulation, NUE , N and P uptake efficiency (NUtE and NUtE ) P N P were decreased with increase of drought stress regardless of N supply. On the other hand, the S. davidii seedlings exhibited strong responses to N supply, but the responses were inconsistent with the various N supply levels. Low N supply rather than the other two N treatments increased C, N and P accumulation, improved NUEP, NUtE and NUtE under corresponding water condition. In contrast, high N supply N P did few even depressed effects on C, N and P accumulation, and NUEP, although NUtEN and NUtEP could increase with high N supply under corresponding water conditions. Even so, a decrease of NUEN was observed with increase of N supply under corresponding water conditions. 4) Soil microbial and chemical characters in respond to drought stress and N supply The content of soil organic C, available N and P were decreased with increase of drought stress. Decreases in C/N and C/P, and invertase, urea and alkaline phosphatase activity were also observed under drought stress conditions, indicating a lower N and P mineralization rate. Although microbial biomass C, N and P showed slight responses to drought stress after one growth period treatment, microbial biomass C and N were also decreased with increase of drought stress after two year continuous treatment. The content of soil organic C and available P showed the stronger positive responses to low N supply than which to high N supply, although than the other two N treatments increased microbial biomass N and invertase activity under severe drought stress condition, even though invertase activity could increase with high N supply treatment under relative well-water conditions. Moreover, low N supply treatment also increased C/P and alkaline phosphatase activity which might result from higher P mineralization, but high N supply did negative effects on alkaline phosphatase activity. 5) The growth characteristics of Sophora davidii seedlings and soil microbial and chemical characters in respond to N supply under field condition Low N supply facilitated seedlings growth by increasing leaf number, basal diameter, root length, biomass production, C, N and P accumulation and absorption, and enhancing the use efficiency of other limited resources as P. Compared to control, however, low N supply did little effect on altering biomass, C, N and P portioning in seedlings components. On the contrary, high N supply treatment also increased leaf number, biomass and C, N and P accumulation relative to control, but significantly decreased root length, and altered more biomass and resources to above-ground, which strongly reduced the ability of absorbing water under drought condition, and thus which might deep the drought stress. In addition, N supply increased soil C, N and available N content, but declined pH and showed little effects on P content. Low N supply showed higher values of soil C and available P content. Low N supply also increased microbial biomass C, N and P, although high N supply decreased microbial biomass C. N supply significantly enhanced soil invertase, urea, alkaline and neutral phosphratase activity, while declined acid phosphratase and catalase activity. Low N supply exhibited higher alkaline and neutral phosphratase activity compared to the others. The results from this study indicated that both drought and N limited the growth of S. davidii seedlings and their biomass production. Regardless of N supply levels, drought stress dramatically reduced the seedlings growth and biomass production. Although plant growth parameters, including basal diameter, height, leaf number, and biomass and their components were observed to be positive responses to low N supply, N supply alone can not alter the diminishing tendency which is caused by drought. available N content increased with increase N supply. In addition, low N supply rather These findings imply that drought played a primary limitation role and N was only the secondary. Even so, appropriate N supply was seemed to enhance the ability that S. davidii seedlings adapted to the xeric and infertile environment by improving soil processes, stimulating plant growth, increasing recourses accumulation, enhancing use efficiency of other limited resources, and balancing biomass and resources partitioning. Appropriate N supply, therefore, would be recommended to improve S. davidii seedling establishment in this region, but excess N supply should be avoided.

川西云杉(Picea balfouriana)天然群体的遗传变异

青藏高原东南缘由于特殊的生态地理条件，有着丰富的森林资源，这些资源是长江上游涵养水源、保持水土的生态屏障，是生物多样性的资源宝库。但随着过量的森林采伐，使该区曾经丰富的生物多样性资源遭受了前所未有的破坏，天然林的质量严重下降，生态系统退化，功能减弱。与此同时，许多物种的种群规模正在锐减，物种的遗传多样性也严重丧失。川西云杉是西部地区分布最广的云杉树种之一，在较高海拔的地区有着重要的生态学功能，是一种适应性很强的乡土树种。本项目采用简单序列重复标记(SSR)和特定序列位点(STS)研究不同生境条件下川西云杉群体的遗传变异及其时空分布格局，考察遗传变异与复杂的山地生态环境间的潜在联系，系统地揭示川西云杉天然群体与环境系统相互作用的生态适应与分子进化机制。研究成果能有效地为该树种遗传资源的科学保护与合理利用提供理论依据和科学指导，可为中国西南部亚高山天然林的可持续经营及退化生态系统的恢复与重建提供依据。主要研究结果如下： 1 STS和SSR两种分子标记的研究结果表明：川西云杉群体拥有中等水平的遗传多样性(基于SSR标记，平均He = 0.640；基于STS标记，平均He = 0.553)。造成这种中等水平的遗传多样性，可能是由于历史原因，川西云杉天然林被大量采伐，导致了遗传多样性的丧失。两种方法都检测出群体BT有着最高水平的遗传多样性。 2 两种标记的结果都一致说明：检测的10个川西云杉群体间遗传分化比较高，其存在群体间的遗传变异比例要明显地高于广泛分布的挪威云杉、横贯大陆的黑云杉以及兼有连续分布和不连续分布的西加云杉等，但要低于分布范围狭窄且呈不连续分布的粗枝云杉。青藏高原东南部的片段化生境可能是导致高水平遗传分化的主要原因。 3 基于两种标记的UPGMA 聚类和PCA分析结果，以及基于SSR标记的FCA分析结果都显示：群体BY遗传上明显区别于其它群体，其可能原因是青藏高原东南缘山脉阻隔而导致的生殖隔离的结果。 4 根据软件Bottleneck 1.2.02的检测以及不依赖哈迪一温伯格平衡的M比率检测结果：川西云杉种群很有可能经历了近期的遗传瓶颈效应。在本研究中遗传瓶颈效应并没有显著影响到物种的遗传多样性。然而，在这些片断化群体未来的子代群体中很可能出现遗传瓶颈导致的遗传多样性下降的效应。 Due to the extremely complex topography and climatic conditions, the southeast of the Qinghai-Tibet Plateau is region abundant in forest resource, which is benefit to the upper reaches of the Yangtze River water conservation, and protecting natural environment and biodiversity resources. However, by the reason of a plenty of trees were cut in these yeas, the biodiversity resource was destroy with degraded ecosystem and imperfect funcation. Picea balfouriana is one of the regionally distributed conifer species in the southeast of the Qinghai-Tibet Plateau and considered as a constructive species within its distribution area. It is an optimal species for the production of biomass. Moreover, it is well adapted to stressful environments at high altitude, especially to cold and drought conditions which are generally harsh for other trees. In our study, two types of molecular markers (SSR and STS) were used to estimate the genetic diversity and genetic structure of P. balfouriana populations originating from the southeast of the Qinghai-Tibet Plateau with varying climatic and geographical conditions. The results will not only provide a deep insight into its genetic diversity and population genetic structure but also valuable information for further management and breeding programs in P. balfouriana. In summary, the results obtained in this study revealed that: 1 A moderate degree of genetic variation is present in P. balfouriana in the southeast of the Qinghai-Tibet Plateau and it may caused by many trees were cut in the past. Population BT owns the highest level of genetic diversity by both two types of markers. 2 Considerable population differentiation exists among the ten P. balfouriana populations based on both SSR and STS markers, possibly caused by habitat fragmentation and heterogeneous environments. 3 The UPGMA clustering and PCA analyses based on SSR and STS marker, and FCA analyses based on SSR marker congruously separated population BY from other populations, which is likely due to the presence of mountain barriers. 4 The results of bottleneck analysis indicated that P. balfouriana populations that have undergone recent declines. In our research, the bottleneck effect don’t have a significant impact on the genetic diversity of species, however, the level of genetic diversity of P. balfouriana offspring populations growing in the fragmented habitats will decline in the future.

一株掷孢酵母利用红薯淀粉酶解液积累油脂研究

本论文以红薯淀粉的双酶法水解液为碳源，从19 株红色酵母中筛选出一株油脂含量较高的菌株掷孢酵母（Sporobolomyces reseus）As.2.618。为了提高掷孢酵母（S.reseus）As.2.618 的油脂产量，考察了培养基组成对该菌生长情况及油脂积累的影响。用均匀设计法对培养基组成进行了优化，由DPS软件得出的优化结果为：还原糖103g/L、酵母粉11.5g/L、磷酸二氢钾0.3g/L、硫酸镁0.15g/L。生物量可达19.23 g/L,油脂含量为3.875 g/L。研究了添加二价离子对该菌的生长及油脂积累的影响,结果表明Zn2+对该菌生长和油脂积累都有显著促进作用。研究了发酵条件以及添加氧载体正十二烷对该菌发酵的影响，表明添加正十二烷有利用于该菌生长与油脂积累。得出最佳发酵条件是：在还原糖103g/L、酵母粉11.5g/L、磷酸二氢钾0.3g/L、硫酸镁0.15g/L。添加30mg/L 硫酸锌,接种量为5％，在24h 后添加2g/L 的碳酸钙和2%(v/v)正十二烷，pH6.0 培养温度为27℃，转速为200r/min，培养时间为7 天的条件下，该菌生物量干重可达35.05g/L,油脂含量也达11.98g/L。Lipid is one of the basic material for life-sustaining activities andimportant industrial materials. As lipid resources mainly come from the animal andthe plant, the problem of lipid lack is encountered at times. The lipid frommicroorganisms is the substitute and superior to the above lipid with a short period ofproduction and much cheaper fermentation materials such as agricultural and sidelineproducts or wastes of crop.Thus large scale production and broad application ofmicrobial lipid will be efficient not only in substitute of the animal and the plant lipidfor food and industrial field , but also inducing a new way leading to solve the energyproblem.For the purpose of exploring the characteristics of lipid production of redyeasts from sweet potato starch hydrolysates. 19 red yeasts are screened for thecapability of lipid producing and one strain Sporobolomyces reseus As.2.618 withsuperior performance is sellected.To improve the Sporobolomyces reseus As.2.618’s capability of lipidaccumulation , the components of the medium, which may influence the growth of thestrain and the lipid yield have been studied. To get the optimum mediumcomponents ,the “uniform design” was used .The DPS software gave the optimummedium component is: reducing sugar 103 g/L、yeast extract 11.5 g/L、KH2PO4 0.3g/L、MgSO4 0.15 g/L. The biomass could reach up to 19.23 g/L and lipid yield 3.87g/L with the above composition of fermentation medium.Furthermore the fermentation conditions , addition of the divalent metal ionsand the oxygen vector to increase the strain’s lipid producing capability are tested.The optimum condition is : reducing sugar 103 g/L、yeast extract 11.5 g/L、KH2PO40.3 g/L、MgSO4 0.15 g/L，Adding 30mg/L ZnSO4,and adding 2g/L CaCO3 2％(v/v)n-dodecane after 24h’s fermentation. the optimal fermentation condition were asfollow :30ml medium in the 500ml flask with initial pH 6.0,the flasks with 5%inoculation volume were at 200r/min shaking speed for 7d’s fermentation at27 .Under this kind of condition the high biom ¡æ ass which reach to 35.05 g/L could begot ,the yield of lipid also could reach to 11.98g/L.

组合白腐真菌预处理木质纤维素原料的研究

木质纤维素原料种类多、分布广、数量巨大，通过燃料乙醇生产技术、厌氧沼气发酵技术将其转化成乙醇、沼气等二次能源，一定程度上可以缓解化石能源的不断消耗所带来的能源危机，也解决了农林废弃物引起的环境污染问题。其中以木质纤维素原料生产燃料乙醇，还可以避免以淀粉类和糖类原料生产燃料乙醇时带来的“与人争粮”等一系列问题。因此具有重要的经济效益、环境效益和社会效益。 然而，木质纤维素原料结构致密，木质素包裹在纤维素、半纤维素外围，导致其很难被降解利用，必须进行适当的预处理，去除木质素，打破原有的致密结构，利于原料的后续利用。因此，预处理成为木质纤维素原料能源化利用的关键。而目前预处理环节的费用过于昂贵，于是寻找一种高效、低成本的预处理方法是当今研究的热点。 本论文采用组合白腐真菌对木质纤维素原料进行生物预处理研究，与其他物理化学法相比，该法有着专一性较强、反应温和、不造成环境污染、成本低等优势。白腐真菌主要通过分泌木质素降解酶对木质素进行降解，从而破坏原料的致密结构，提高后续利用效率。所以木质素降解酶酶活的高低是影响原料预处理效果的一个关键因素。于是本论文首先通过将白腐真菌进行组合的方式提高木质素降解酶（漆酶，Lac）酶活；接着对组合菌的菌株相互作用机理进行研究，阐明组合菌Lac 酶活提高的原因，为菌株组合提高Lac 酶活这种方法的应用提供理论依据，同时也为后续组合白腐真菌预处理木质纤维素原料提供指导；进一步采用固态发酵和木质素降解酶两种方式对木质纤维素原料进行预处理研究，最大化去除木质素成分，破坏原料的致密结构；最终对预处理后原料的酶解糖化进行初步研究，为原料后续的能源化应用奠定基础。具体研究结果如下： （1） 以实验室保存的三株主要分泌Lac 的白腐真菌为出发菌株，筛选得到一组Lac 酶活明显提高的组合菌55+m-6，其中菌株55 为Trametes trogii sp.，m-6 为Trametes versicolor sp.，组合后Lac 酶活较单菌株分别提高24.13倍和4.07 倍。组合菌的最适产酶条件为pH 6.5、C/N 16:1、Tween 80 添加量为0.01%，在该条件下组合菌的Lac 酶活峰值比未优化时提高4.11倍。 （2） 对组合菌55+m-6 菌株间相互作用机理进行研究，发现菌株之间不存在抑制作用；平板培养时，菌丝交界处Lac 酶活最高并分泌棕色色素；液体培养时，菌株m-6 对组合后Lac 酶活的提高起着更为重要的作用：菌株m-6的菌块、过滤灭菌胞外物以及高温灭菌胞外物均能明显刺激菌株55 的Lac产生；菌株55、m-6 进行组合后，同工酶种类未发生增减，但有三种Lac同工酶浓度有所提高；对菌株胞外物进行薄层层析和质谱分析，结果表明组合前后菌株胞外物中各物质在浓度上存在较大的变化。推测组合菌Lac酶活的明显提高，主要是由于菌株m-6 胞外物中的一些物质能刺激菌株55 分泌大量Lac 进行代谢，且这些刺激物质并非菌株m-6 特有，菌株55自身也可以代谢生成，但是适当的浓度才能刺激Lac 的大量分泌。 （3） 将组合菌55+m-6 用于固态发酵预处理木质纤维素原料，发现其对玉米秆的降解程度最大，在粉碎度40 目、含水率65%的最优处理条件下，处理至第15d，秸秆失重率为41.24%，其中木质素、纤维素、半纤维素均有降解，且Lac 和纤维素酶（CMC）酶活以及还原糖量均达到峰值。 （4） 对玉米秆进行木质素降解酶预处理，发现Lac/1-羟基苯并三唑（HBT）系统对玉米秆木质素的降解效果最好，在最优处理条件时，即HBT 用量0.2%、处理时间1d、Lac 用量50U/g，木质素降解率可达12.60%。预处理后玉米秆的致密结构被破坏，比表面积增大，利于后续酶与纤维素、半纤维素成分的结合。 （5） 对预处理后的玉米秆进行酶解糖化，其中组合菌固态发酵预处理后玉米秆的糖化率比对照高4.33 倍；Lac/HBT 系统预处理后玉米秆的糖化率比对照高2.99％，糖化液中主要含有木糖、葡萄糖两种单糖。 There are many kinds and large quantities of lignocellulosic biomass widely distributed on the earth. They can be converted into secondary energy such as fuel ethanol, biogas, et al., which can relieve the energy crisis caused by consumption of fossil energy resources and solve the problem of environmental pollution caused by agriculture and forestry waste. Meanwhile, the production of fuel ethanol from lignocellulosic biomass can ensure food supply to human kind instead of starch- and sugar-containing raw materials. So the energy conversion of lignocellulosic biomass contributes considerable economic, environment and social benefits. However, lignocellulosic biomass has the compact structure, in which lignin surrounds cellulose and hemicellulose, so it must be pretreated before energy usage and pretreatment is one of the most critical steps in the energy conversion of lignocellulosic biomass. At present, the cost of pretreatment is too expensive, so looking for an efficient and low-cost pre-treatment method is one of recent research hot spots. In this research, combined white rot fungi pretreatment method was used, which had some advantages in low cost, high specificity, mild reacting conditions and friendly environmental effects compared with the other physical and chemical methods. White rot fungi secrete lignin degrading enzymes to degrade the content of lignin and damage the contact structure of lignocellulosic biomass, so the activity of the lignin degrading enzymes is the key factor to the degradation effect of raw materials. Firstly, the combined fungi with high laccase activity were screened; secondly, the interaction mechanism between strains was studied, and the cause of higher laccase activity after strains combination was also preliminary clarified; under the guidance of the mechanism, lignocellulosic biomass was pretreated by the combined fungi; lastly, the enzymatic hydrolysis of pretreated lignocellulosic biomass was also preliminary studied; all of the researches could lay the foundation for the energy application of lignocellulosic biomass. The specific research results were as follows: (1) The combined fungi 55+m-6 with significant higher laccase activity were screened from the three white rot fungi stored in our lab which mainly secreted laccase. Strain 55 and strain m-6 were Trametes trogii sp. and Trametes versicolor sp., respectively. The laccase activity of combined fungi was 24.13 and 4.07-fold than strain 55 and strain m-6, respectively. The optimized condition for laccase production of the combined fungi in liquid medium was pH 6.5, C/N 16:1 and Tween 80 0.01%. In this optimized condition, the laccase activity of combined fungi was 4.11-fold higher comparing with which in non-optimized medium. (2) The interaction mechanism between strain 55 and strain m-6 was further studied, and no inhibition effect was observed. Brown pigment was secreted on the junction of the two strains on the plate, where the highest laccase activity was detected. Strain m-6 was much important to boost laccase activity of combined fungi in liquid medium, and strain 55 was stimulated by fungal plug, filter sterilized extracellular substances and high temperature sterilized extracellular substances of strain m-6 to produce laccase. The types of laccase isozymes did not change after combining strain 55 and strain m-6, but the concentrations of three types increased. Mass Spectrometry and TLC analysis of extracellular substances of each strain showed that concentration of some substances considerably changed after strains were combined. It was supposed that the cause of higher laccase activity of combined fungi was mainly due to some extracellular substances of strain m-6 with the appropriate concentration which stimulated laccase secretion of strain 55 and generated not only by strain m-6 but also by strain 55. (3) Combined fungi 55+m-6 were used to lignocellulosic biomass pretreatment with the type of solid-state fermentation. The highest degree of degradation of corn straw was obtained, including the rate of weight loss was 41.24% and the lignin, cellulose and hemicellulose were degraded partially under the optimized condition of 40 mesh, 65% water content on 15th day. Laccase, CMCase activities and content of reducing sugar reached the maximum value on that day. (4) Lignin degrading enzymes from combined fungi 55+m-6 were used for corn straw pretreatment. The most remarkable degradation of lignin in corn straw with Lac/1-hydroxybenzotriazole (HBT) system was observed, and the 12.60% lignin degradation was obtained under the optimized condition of 0.2% HBT, 50 U/g laccase for 1 d. After pretreated by Lac/HBT, the tight structure of corn straw was demolished and specific surface area increased, which had advantages for accessible of enzyme to cellulose and hemicellulose. (5) The corn straws pretreated by combined fungi 55+m-6 with the type of solid-state fermentation and Lac/HBT were used for enzymatic hydrolysis, and the saccharification rates of each pretreatment type were 4.33 times and 2.99% higher than CK, respectively. The enzymatic hydrolysis liquid of corn straw pretreated by Lac/HBT mainly contained xylose and glucose.

Multiple expansions of C-4 plant biomass in East Asia since 7 Ma coupled with strengthened monsoon circulation

IEECAS SKLLQG

Surface pigments,algal biomass profiles,and potential production of the euphotic layer:Relationships reinvestigated in view of remote-sensing applications

Maps of surface chlorophyllous pigment (Chl a + Pheo a) are currently produced from ocean color sensors. Transforming such maps into maps of primary production can be reliably done only by using light-production models in conjuction with additional information about the column-integrated pigment content and its vertical distribution. As a preliminary effort in this direction. $\ticksim 4,000$ vertical profiles pigment (Chl a + Pheo a) determined only in oceanic Case 1 waters have been statistically analyzed. They were scaled according to dimensionless depths (actual depth divided by the depth of the euphotic layer, $Z_e$) and expressed as dimensionless concentrations (actual concentration divided by the mean concentration within the euphotic layer). The depth $Z_e$ generally unknown, was computed with a previously develop bio-optical model. Highly sifnificant relationships were found allowing $\langle C \rangle_tot$, the pigment content of the euphotic layer, to be inferred from the surface concentration, $\bar C_pd$, observed within the layer of one penetration depth. According to their $\bar C_pd$ values (ranging from $0.01 to > 10 mg m^-3$), we categorized the profiles into seven trophic situations and computed a mean vertical profile for each. Between a quasi-uniform profile in eutrophic waters and a profile with a strong deep maximum in oligotrophic waters, the shape evolves rather regularly. The wellmixed cold waters, essentially in the Antarctic zone, have been separately examined. On average, their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values their profiles are featureless, without deep maxima, whatever their trophic state. Averaged values of $ρ$, the ratio of Chl a tp (Chl a + Pheo a), have also been obtained for each trophic category. The energy stored by photosynthesizing algae, once normalized with respect to the integrated chlorophyll biomass $\langle C \rangle _tot $ is proportional to the available photosythetic energy at the surface via a parameter $ψ∗$ which is the cross-section for photosynthesis per unit of areal chlorophyll. By tanking advantage of the relative stability of $ψ∗.$ we can compute primary production from ocean color data acquired from space. For such a computation, inputs are the irradiance field at the ocean surface, the "surface" pigment from which $\langle C \rangle _tot$ can be derived, the mean $ρ value pertinent to the trophic situation as depicted by the $\bar C_pd or $\langle C \rangle _tot$ values, and the cross-section $ψ∗$. Instead of a contant $ψ∗.$ value, the mean profiles can be used; they allow the climatological field of the $ψ∗.$ parameter to be adjusted through the parallel use of a spectral light-production model.

土壤改良剂与氮肥配施对玉米生长及其养分含量的影响

采用盆栽试验研究了秸秆配方、废料配方和胶土配方3种改良剂与氮肥配施对玉米植株生长状况、生物量、叶绿素含量、全N及全P含量的影响。结果表明:3种改良剂与0.5 g/盆氮肥配施可以显著提高株高、茎粗、叶面积、地上地下生物量、叶绿素含量及植株全N含量,且以秸秆配方配施效果最佳,过量施用氮肥(1.0 g/盆)时,各指标与0.5 g氮肥水平下的值相比增加幅度甚小,茎粗和地下生物量甚至有下降的趋势。改良剂因素和氮肥因素对全P含量也有一定的影响,但二者交互作用对其并未产生显著性影响。因此,在施加改良剂的条件下可以适当地减少肥料的使用量,在满足植物体吸收利用前提下,既减少了养分投入和浪费,又减轻了对环境的污染。

密度对刺槐幼苗生物量及异速生长模式的影响

刺槐(Robinia pseudoacacia)具有较强的生态适应性和抗逆能力,是黄土高原植被恢复和生态重建的主要优良树种之一(程积民等,2002;陈云明等,2002)。黄土高原地区刺槐人工林密度偏大,且多为低产林(余新晓等,1996;韩芯莲等,1996;2003)。王百田等(2005)认为黄土高原刺槐单木总生物量及各部分生物量都是密度的幂函数关系,但低密度林分和高密度林分的总生物量都比中间密度林分的总生物量高。种植密度不仅影响刺槐林地生物量,而且刺槐林地出现土壤干层的部分原因就是栽植密度过大(韩芯莲等,2003),其林地生产力的维持以及可持续生长成为林草植被建设中亟待解决的问题。植物密度对种群个体数量和生长的调控可以维持种群对资源的合理利用,保持种群的稳定性(Watkinson,1980)。因生长资源的强制分配,种植密度能引起植株个体间相互作用,密度增加导致植物种内竞争产生,使种群中单株生长量和生物量发生改变(李博等,2000)。竞争的实质是植物对地上光照和地下养分资源的利用,在共享资源有限的情况下竞争会导致植物个体生长量和存活率的降低(李博等,1998)。种内竞争对植物个体生长的影响,与植物“自疏法则”的...

Spatial and temporal flows of China's forest resources: Development of a framework for evaluating resource efficiency

Science & Technology Basic Work Program of China: Scientific Survey of the Middle-lower Reaches of Lantsang River and the Great Shangri-La Region [2008FY110300]; National Basic Research Program of China (973 Program): Ecosystem Services and Ecological Safety of the Major Terrestrial Ecosystems of China [2009CB421106]; National Natural Science Foundation of China [30670374]; EU ; European Commission, DG Research [003874]

Evaluation for use efficiency of agricultural resources in grain production: A case study of Changshu, Taihe and Ansai in China

National Natural Science Foundation of China [70673097]

Changes in individual plant traits and biomass allocation in alpine meadow with elevation variation on the Qinghai-Tibetan Plateau

Plant traits and individual plant biomass allocation of 57 perennial herbaceous species, belonging to three common functional groups (forbs, grasses and sedges) at subalpine (3700 m ASL), alpine (4300 m ASL) and subnival (>= 5000 m ASL) sites were examined to test the hypothesis that at high altitudes, plants reduce the proportion of aboveground parts and allocate more biomass to belowground parts, especially storage organs, as altitude increases, so as to geminate and resist environmental stress. However, results indicate that some divergence in biomass allocation exists among organs. With increasing altitude, the mean fractions of total biomass allocated to aboveground parts decreased. The mean fractions of total biomass allocation to storage organs at the subalpine site (7%+/- 2% S.E.) were distinct from those at the alpine (23%+/- 6%) and subnival (21%+/- 6%) sites, while the proportions of green leaves at all altitudes remained almost constant. At 4300 m and 5000 m, the mean fractions of flower stems decreased by 45% and 41%, respectively, while fine roots increased by 86% and 102%, respectively. Specific leaf areas and leaf areas of forbs and grasses deceased with rising elevation, while sedges showed opposite trends. For all three functional groups, leaf area ratio and leaf area root mass ratio decreased, while fine root biomass increased at higher altitudes. Biomass allocation patterns of alpine plants were characterized by a reduction in aboveground reproductive organs and enlargement of fine roots, while the proportion of leaves remained stable. It was beneficial for high altitude plants to compensate carbon gain and nutrient uptake under low temperature and limited nutrients by stabilizing biomass investment to photosynthetic structures and increasing the absorption surface area of fine roots. In contrast to forbs and grasses that had high mycorrhizal infection, sedges had higher single leaf area and more root fraction, especially fine roots.